JP3324619B2 - Package leak measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package leak measuring device used for testing the leak of a package in which food, medicine and the like are hermetically sealed.

[0002]

2. Description of the Related Art As a conventional apparatus of this kind, there is an apparatus invented by the same person as the inventor of the present invention (Japanese Patent Application No. 78071 in 1988). The apparatus includes a chamber for receiving a package to be tested, a vacuum pump, an exhaust pipe communicating the interior of the chamber with the vacuum pump, a valve provided in the exhaust pipe for opening and closing an exhaust flow path, In a device comprising a measurement control unit that measures the internal pressure and controls the valve, provided with a leak valve configured to leak outside air between the valve and the vacuum pump in the exhaust passage, The outside air leak amount of the leak valve is increased as the chamber internal pressure approaches the set value, so that the discharge speed of the air in the chamber is reduced immediately before closing the exhaust flow path,
The pulsation of the chamber internal pressure generated immediately after the exhaust passage is closed is reduced, and the chamber internal pressure is stabilized in a short time.

[0003]

In the above-mentioned conventional apparatus, the pulsation of the internal pressure of the chamber immediately after the closing of the exhaust passage is small, so that the variation value of the internal pressure of the chamber after the closing of the exhaust passage is small.
Also, it has the advantage that the accuracy of the actual pressure with respect to the set pressure is also high, but since the air discharge speed in the chamber immediately before closing the exhaust passage is slow, if there is a large hole in the test package,
There is a problem that the pressure inside the package is also reduced, so that the package may be erroneously determined as a non-defective product.

The problem to be solved by the present invention is to eliminate the erroneous determination by exhausting the air in the chamber at a high speed until the pressure in the chamber reaches a set value. The chamber pressure transiently reduced by the overshoot generated when the flow path is closed can be returned to the set value, and the pulsation of the chamber pressure generated when the exhaust flow path is closed is suppressed. It is another object of the present invention to provide a test apparatus in which the time required from the start of discharge of air in the chamber to the time when the pressure in the chamber stabilizes at a set value is reduced, and the time required for a leak test of the package is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a chamber for receiving a package to be inspected, a vacuum pump, and a communication between the inside of the chamber and the vacuum pump. An exhaust pipe, a valve provided in the exhaust pipe for opening and closing the exhaust flow path, and a measurement control unit for controlling the opening and closing of the valve by measuring an internal pressure of the chamber; An air storage container that stores a predetermined volume of air is provided via an exhalation tube that communicates the inside of the two, and a valve that opens and closes the exhalation flow path of the exhalation tube under the control of the measurement control unit is provided in the exhalation tube, A control valve for discharging air in the air storage container into the chamber for a predetermined time is provided in the exhaust pipe.

If the package to be inspected is weak and may be damaged by the overshoot, in addition to the above-described means, a leak valve configured to leak outside air to the air discharge pipe in the chamber. It is preferred to use

[0007]

When the pressure reaches a set value while the air in the chamber is exhausted at a high speed, the air exhaust passage is closed.
The chamber internal pressure exceeds the set value and overshoots to a negative pressure. When a valve provided in the exhalation tube is opened, a predetermined amount of air is discharged into the chamber for a predetermined time, and a predetermined positive pressure is applied to the chamber. When a predetermined positive pressure is applied to the chamber, the chamber internal pressure exceeding the set value due to the negative pressure overshoot is returned to the set value. At the same time, the pulsation of the chamber internal pressure is suppressed.

When a leak valve for leaking outside air is used together with the air discharge pipe in the chamber, the discharge speed of the air in the chamber becomes slower as the pressure in the chamber approaches the set value, and the air discharge passage in the chamber is closed. The overshoot of the chamber internal pressure occurring at the time of is reduced, and the pulsation is further suppressed.

FIG. 3 shows changes in the internal pressure of the chamber in each of the apparatus of the present invention and the conventional apparatus. In this figure, the vertical axis P indicates the chamber internal pressure, the horizontal axis T indicates time, and PS
A is a set value, A is a pressure change in the device of the present invention provided with only the air container, B is a pressure change in the device of the present invention using both the air container and the leak valve, and C is a set value. The pressure change in a conventional device provided with only a leak valve is indicated by a dashed line D is the pressure change when the air in the chamber is discharged at a speed along the line A, and neither the air container nor the leak valve is used. , A indicates a point in time when the air discharge channel is opened, and ma, mb, and mc indicate points in time at which the pressure is stabilized.

[0010]

FIG. 1 is a conceptual diagram showing a first embodiment of the present invention. In this figure, reference numeral 20 denotes a chamber, which is provided with an opening / closing section (not shown) for taking in and out the package 22 to be tested, and which can be hermetically sealed. The shape and size of the chamber are manufactured in consideration of the shape and size of the package to be inspected. 24 is a vacuum pump, 26 is an exhaust pipe, 28 is an outside air outlet, 30 is an electromagnetically driven vacuum valve, and 32 is a vacuum pump drive motor. 34 is an air cylinder, that is, an air container. 36 is an air discharge channel, and 38 is an electromagnetic valve. 4
Numeral 0 indicates that the flow rate can be adjusted by an air flow rate control valve.
The air cylinder 34 is bolted to a member that defines the air discharge passage 36 via a flange so that the cylinder can be replaced. The volume of the cylinder is selected based on the set value of the pressure in the chamber and the remaining space after the subject is placed in the chamber, and is approximately 1 to 5% of the volume of the chamber. Reference numeral 42 denotes a chamber pressure detector, which is connected to an input circuit of the measurement control unit 44. An electromagnetic valve 46 opens and closes an air flow path between the inside and the outside of the chamber. 48 is an outside air inlet. The electromagnetic valves 30, 38, 46 and the motor 32 are controlled by the measurement control unit 44, and the setting of the chamber internal pressure is performed based on the atmospheric pressure.

Next, the operation of the first embodiment will be described. When the electromagnetic valve 46 is open, the pressure in the chamber becomes equal to the atmospheric pressure, and the chamber is in a state where the package to be tested can be taken in and out. At this time, the electromagnetic valve 38 is also open, and the internal pressure of the air cylinder 34 becomes equal to the atmospheric pressure. When the package 22 to be tested is placed in the chamber, the electromagnetic valves 38 and 46 are closed, and the vacuum pump 24 is driven, the pressure in the chamber is reduced. When the chamber pressure reaches the set value, the valve 30 is closed. When the valve 30 is closed, the chamber internal pressure overshoots to a negative pressure and is reduced to a value exceeding a set value. Valve 3
The valve 38 is opened 0.1 to 0.2 seconds after the 0 is closed, the air discharge passage 36 is opened, and the air in the cylinder 34 is discharged into the chamber. When the air in the cylinder is discharged, a positive pressure is applied to the chamber, and the pressure in the chamber, which has been reduced to a value exceeding the set value, is returned to the set value. When the air flow rate of the air flow rate control valve 40 is adjusted, the time required for discharging the air becomes constant even if the volume of the air cylinder 34 is changed. Referring to FIG. 3, the chamber internal pressure changes along curve A, and stabilizes when it reaches the point ma. A change in the chamber internal pressure for a predetermined time from that point is measured. Is determined.

Since the setting of the chamber internal pressure is performed on the basis of the atmospheric pressure, the difference between the cylinder internal pressure and the chamber internal pressure when the chamber internal pressure reaches the set value is always constant.

Next, a second embodiment will be described with reference to FIG. The second embodiment differs from the first embodiment in that a leak valve 50 is provided.
Is added. This leak valve 50
Are provided in the exhaust pipe 26 so that outside air leaks into the exhaust pipe. 52 is an outside air inlet.

Next, the operation of the second embodiment will be described.
The leak amount of the leak valve 50 increases as the pressure in the chamber increases. Therefore, the pressure reduction rate in the chamber becomes slower as the chamber pressure approaches the set value. When the valve 30 is closed in a state where the decompression speed is slow, the overshoot is smaller than when the valve is closed in a state where the decompression speed is faster. When the valve 38 is opened and the air in the cylinder 34 is discharged into the chamber,
The discharged air acts in the same manner as in the first embodiment when the air in the cylinder 34 is discharged. This action, together with the action of the leak valve 50, makes the overshoot and the pulsation smaller than in the device of the first embodiment.

[0015]

According to the present invention, after the air discharge passage in the chamber is closed, a predetermined amount of air is discharged into the chamber for a predetermined time, thereby setting an excessively reduced pressure in the chamber caused when the discharge passage is closed. Value and at the same time suppress the pulsation of the chamber internal pressure, so that the pressure inside the chamber can be reduced at a high speed and the internal pressure of the chamber can be stabilized at a set value in a short time. The time required for the internal pressure to stabilize at the set value is shortened, so that the work efficiency in the leak test of mass-produced packages of foods, medicines, etc. can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing one embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a change in chamber internal pressure by comparing the first embodiment of the present invention, the second embodiment of the present invention, and a conventional apparatus.

[Explanation of symbols]

 Reference Signs List 20 chamber 22 package to be inspected 24 vacuum pump 26 exhaust pipe 30, 38 valve 34 air container (air cylinder) 36 gas discharge pipe (air discharge flow path) 40 control valve 44 measurement control unit 50 leak valve

Claims (2)

(57) [Claims] A vacuum pump, an exhaust pipe communicating between the inside of the chamber and the vacuum pump, and an exhaust flow provided in the exhaust pipe. In a package leak measurement device including a valve 30 for opening and closing a passage and a measurement control unit 44 for measuring the internal pressure of the chamber 20 and controlling the opening and closing of the valve 30, an air container for containing a predetermined volume of air in the chamber 20 A container 34 is provided via an exhalation tube 36 communicating the inside of the container 34 and the exhalation tube 36
A valve 38 for opening and closing the exhalation flow path of the exhalation tube 36 under the control of the measurement control unit 44;
A package leak measuring device, further comprising an air flow control valve 40 for adjusting the cross-sectional area of the discharge passage. 2. A chamber 20 in which a package 22 to be inspected is placed, a vacuum pump 24, an exhaust pipe 26 communicating the inside of the chamber 20 with the vacuum pump 24, and an exhaust flow provided in the exhaust pipe 26. A valve 30 for opening and closing a passage, a measurement control unit 44 for measuring the internal pressure of the chamber 20 and controlling the opening and closing of the valve 30, and the exhaust pipe 2 provided between the vacuum pump 24 and the valve 30.
6. A package leak measuring device comprising: a leak valve 50 for leaking outside air into the chamber 6;
An air container 34 for accommodating a predetermined volume of air is provided via an exhalation tube 36 communicating between the two, and the exhalation flow path of the exhalation tube 36 is controlled by the measurement control unit 44 in the exhalation tube 36. A package leak measuring device, comprising: a valve 38 that opens and closes; and an air flow control valve 40 that is capable of adjusting the cross-sectional area of the gas discharge passage in the gas discharge pipe 36.